I have a little system that takes a .git and mounts it as a fuse filesystem. Every commit becomes a directory with a snapshot of the project at that point in t

I have a little system that takes a .git and mounts it as a fuse filesystem. Every commit becomes a directory with a snapshot of the project at that point in time. You could read the whole .git in at once, and then you'd have an in-memory file-system, if you wanted to. In any case, I agree with you: it's not about mocking.